The 22% withholding trap,
quantified for your situation
Federal supplemental withholding on RSU vests is a flat 22%. For senior tech professionals, the marginal bracket is 32-37%. The gap surfaces in April. This calculator tells you how big the gap is, in dollars, for your specific income and vesting profile.
Your inputs
Your income and equity
Your withholding gap
What you'll likely owe in April
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Approximate under-withholding on this year's RSU vests
Enter your numbers to see the calculation.
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Your marginal federal tax bracket (estimated)
If you have multiple vesting events, ESPP, or AMT exposure, this estimate is incomplete. A 30-minute conversation can tell you the actual gap and the quarterly-payment strategy that closes it.
The strategy MicroTax actually applies
How we close the withholding gap proactively
The under-withholding gap above is the symptom. The real issue is that the IRS treats RSU vests as supplemental wages, withheld at a flat 22%, which is below the bracket of nearly every senior tech executive.
Proactive RSU planning closes the gap before December 31, not after April 15. The specific moves vary by client situation, but the toolkit includes: estimated quarterly tax payments calibrated to actual vesting schedules, W-4 supplemental withholding elections, vesting-month bunching for clients with multiple grants, and tax-loss harvesting against other portfolio positions to offset the gap before year-end.
The estimate above tells you the size of the problem. The conversation tells you which moves to make and in what order, see the tech executives advisory page for the fuller picture.
Assumptions in this calculation
- 2026 federal tax brackets. State taxes not included.
- RSU value treated as fully taxable in the year of vest, at supplemental withholding rate of 22%.
- Marginal rate calculated against total income (W-2 + RSU value combined).
- Excludes Net Investment Income Tax (3.8%), Additional Medicare Tax (0.9%), AMT exposure, and ISO/NSO complications.
- Excludes capital gains tax on shares held post-vest.
- Real outcomes also depend on ESPP enrollment, RSU sell-to-cover behavior, deductions, credits, and other factors not modeled.
This is illustrative, not advice. The figures above are estimates based on simplified federal assumptions. They do not constitute tax advice, financial advice, or a guaranteed projection of outcomes. Personal tax situations involve state taxes, NIIT, AMT, phase-outs, specific deductions, and many other factors not modeled here. Before making any tax-driven financial decision, consult a qualified tax advisor.
A calculator estimates. An advisor delivers
A calculator like this approximates a single dimension of the tax picture. The actual planning involves coordination across vesting events, ESPP windows, AMT exposure, and your broader retirement architecture. We do that work in 30-minute discovery calls, no preparation needed.